Chapter 4L. In-Roadway Lights

Section 4L.01 Application
of In-Roadway Lights

Support:
In-Roadway Lights are special types of highway traffic signals installed
in the roadway surface to warn road users that they are approaching
a condition on or adjacent to the roadway that might not be readily
apparent and might require the road users to slow down and/or come
to a stop. This includes, but is not necessarily limited to, situations
warning of marked school crosswalks, marked midblock crosswalks,
marked crosswalks on uncontrolled approaches, marked crosswalks
in advance of roundabout intersections as described in Sections
3B.24
and 3B.25,
and other roadway situations involving pedestrian crossings.

Option:
The flash rate for In-Roadway Lights may be different from the flash
rate of standard beacons.

Section 4L.02 In-Roadway
Warning Lights at Crosswalks

Standard:
If used, In-Roadway Warning Lights at crosswalks shall be installed
only at marked crosswalks with applicable warning signs. They shall
not be used at crosswalks controlled by YIELD signs, STOP signs,
or traffic control signals.

If used, In-Roadway Warning Lights at crosswalks
shall be installed along both sides of the crosswalk and shall span
its entire length.

If used, In-Roadway Warning Lights at crosswalks
shall initiate operation based on pedestrian actuation and shall
cease operation at a predetermined time after the pedestrian actuation
or, with passive detection, after the pedestrian clears the crosswalk.

If used, In-Roadway Warning Lights at crosswalks
shall display a flashing yellow signal indication when actuated.
The flash rate for In-Roadway Warning Lights at crosswalks shall
be at least 50, but not more than 60, flash periods per minute.
The flash rate shall not be between 5 and 30 flashes per second
to avoid frequencies that might cause seizures.

If used on one-lane, one-way roadways, a minimum
of two In-Roadway Warning Lights shall be installed on the approach
side of the crosswalk. If used on two-lane roadways, a minimum of
three In-Roadway Warning Lights shall be installed along both sides
of the crosswalk. If used on roadways with more than two lanes,
a minimum of one In-Roadway Warning Light per lane shall be installed
along both sides of the crosswalk.

If used, In-Roadway Warning Lights shall be installed
in the area between the outside edge of the crosswalk line and 3
m (10 ft) from the outside edge of the crosswalk. In-Roadway Warning
Lights shall face away from the crosswalk if unidirectional, or
shall face away from and across the crosswalk if bidirectional.

Guidance:
If used, the period of operation of the In-Roadway Warning Lights
following each actuation should be sufficient to allow a pedestrian
crossing in the crosswalk to leave the curb or shoulder and travel
at a normal walking speed of 1.2 m (4 ft) per second to at least
the far side of the traveled way or to a median of sufficient width
for pedestrians to wait. Where pedestrians who walk slower than
normal, or pedestrians who use wheelchairs, routinely use the crosswalk,
a walking speed of less than 1.2 m (4 ft) per second should be considered
in determining the period of operation. Where the period of operation
is sufficient only for crossing from a curb or shoulder to a median
of sufficient width for pedestrians to wait, additional measures
should be considered, such as median-mounted pedestrian actuators.

If used, In-Roadway Warning Lights should be installed
in the center of each travel lane, at the centerline of the roadway,
at each edge of the roadway or parking lanes, or at other suitable
locations away from the normal tire track paths.

The location of the In-Roadway Warning Lights
within the lanes should be based on engineering judgment.

Option:
In-Roadway Warning Lights at crosswalks may use pedestrian detectors
to determine the duration of the operation instead of ceasing operation
after a predetermined time.

On one-way streets, In-Roadway Warning Lights may
be omitted on the departure side of the crosswalk.

Based on engineering judgment, the In-Roadway Warning
Lights on the departure side of the crosswalk on the left side of
a median may be omitted.

Unidirectional In-Roadway Warning Lights installed
at crosswalk locations may have an optional, additional yellow light
indication in each unit that is visible to pedestrians in the crosswalk
to indicate to pedestrians in the crosswalk that the In-Roadway
Warning Lights are in fact flashing as they cross the street. These
lights may flash with and at the same flash rate as the light module
in which each is installed.